Esther Lemus, a Sonoma County deputy district attorney, stood in front of her audience and unfurled the story of Kerry and Jeff, friends who parted ways but rejoined in unhappy circumstances.

Taking 30 Piner High School students from the start of the pair’s friendship in the fourth grade through their sentencing for attempted murder in their late teens, Lemus easily held their attention, her gestures crisp, her sentences definitive.

“Kerry stood and looked at Danny’s body for a few seconds before he ran away,” she said.

Lemus held their attention for close to an hour with her presentation, the second half of a two-hour program that she coordinates called GIFT or “Gun Information for Teens.” The presentation was held at Santa Rosa High School in January, and this week all Piner freshmen will go through it.

The fictional Jeff and Kerry were an object lesson in the consequences of poor choices involving firearms. But the program reflected reality in headlines she displayed from recent shootings in Sonoma County. It also called attention to past mass shootings, from the Sandy Hook massacre in 2012 to the Columbine High School shootings in 1999.

“Can school shootings be prevented?” she asked.

A student who earlier had said he could easily get a gun because his father keeps one at home “to protect our family,” said: “Without infringing on the Second Amendment, school shootings can be prevented if people had guns. In self-defense.”

The program, in place since 1998 in Sonoma County, has two components. Lemus handles the legal impacts of gun violence; the other section covers the medical impacts. On Wednesday, that hour was led by Malissa Opulencia, a trauma services nurse at Santa Rosa Memorial Hospital.

Her presentation included graphic images and descriptions of genuine gunshot wounds.

“If there’s something you don’t want to see, feel free to close your eyes or put your head on your desk — because that’s part of the story I’m going to tell,” the nurse warned the class.

She showed an image of a surgeon working frantically on the wide-open chest cavity of a 17-year-old shot in his chest and abdomen while at a party.